Epidermal-Dermal Interactions of Normal and Diseased Adult Human Skin. We have established a model for long-term cultivation of adult human skin on nude athymic mouse. Epidermal cell kinetic studies were undertaken using normal and lamellar ichthyosis skin grafted to the athymic mouse. Labelling index in lamellar ichthyosis skin was several folds greater than normal skin. Transit time was also accelerated. Epidermal cell kinetics of grafted normal skin was similar to results measured in vivo. Studies are underway to investigate other forms of ichthyosis and psoriasis in this system. Studies are also underway utilizing the skin-nude mouse system to study conservation of regional epidermal specificities and the effect of non-dermal connective tissue on epidermal maintenance. Formation and Structures at the Epidermal-Dermal Junction in Normal And Diseased Human Skin. Studies are underway to selectivity extract structures, particularly basal lamina and anchoring fibrils from the epidermal-dermal junction. Clinical, genetic, and pathologic features of patients with various types of epidermolysis bullosa are being studied to define and classify this confusing group of diseases. Suction blister times were evaluated as a measure of blistering tendency in various types of epidermolysis bullosa. Blistering times were found to be distinctly abnormal in two of the severe forms of epidermolysis bullosa, junctional epidermolysis bullosa and epidermolysis bullosa dystrophica-recessive. Blistering times were within normal limits in other types of epidermolysis bullosa. Blistering times were a useful adjunct in the assessment of these diseases.